1. Field of the Invention
The present invention relates generally to an improved overlash jig. More particularly, the invention relates to a device for pulling cable along an existing line such as the lines between utility poles. The invention more specifically relates to a device for pulling cable that remains in place without introducing slack on the cable when the device is no longer under tension.
2. Background
Utility poles support different types of cables that provide services to consumers. These services may include electricity, cable television, telephone, and internet connections, among others. Often, power companies own the poles that support such cables. The owners usually charge other companies who want to utilize the existing poles to support cables for their particular services.
In order to upgrade services to consumers, such as coaxial or fiber optic cables, between utility poles, companies typically lash one or more new cables to existing cables already connected to the utility poles. A new cable is installed between the utility poles using a device that hangs on and rolls along an existing cable. The new cable is secured to one end of the device and a towrope is secured to the other end of the device. The device is then pulled along the existing cable using the towrope. The new cable follows and is then attached to the existing support cable.
These devices, called overlash jigs, are normally utilized to “pull” a new cable “and keep it in line with” an existing cable. In some embodiments, the rope connects the jig to a vehicle/other towing device or other means for pulling it along the path of the existing cable. In some cases, the cable is pulled by a member of a ground crew.
Generally, the towrope remains continuously under tension and the device pulls a new cable into place. Sometimes, the tension on the towrope may be relaxed accidentally or by necessity. For example, when the vehicle or person towing the device stops, when the tow line breaks, or when an obstacle needs to be overcome. Additionally, when a second pole is encountered in the stringing operation, the pulling stops while the jig is disengaged, moved past the pole, and reengaged. In such situations, the jig may travel backwards due to the new cable's own weight. Such backward travel may result in personal injuries or damage to the cables and equipment. While some prior art devices use clamps to prevent backward motion of the device, they are only used in new construction or initial installation of lines wherein the prior art device rides on a support line, which is basically wire rope approximately ¼″ in diameter. Often new cable is added to existing cable packages, which consist of two or more coaxial/fiber optic cables that were previously overlashed to the support line. This requires a device that will ride on a larger cable package, other than a support line.